1. Field of the Invention
The present invention relates to an organic electroluminescent device with improved luminous efficiency.
2. Description of the Related Art
Organic electroluminescent devices are self-emissive devices that emit light when a current is applied to a fluorescent or phosphorescent organic layer and electrons and holes combine in the organic layer. Organic electroluminescent devices have many advantages including being lightweight, easy to manufacture, and having high resolution and wide viewing angles. Further, organic electroluminescent devices can display moving pictures with high color purity, and have low power consumption and low driving voltage. These advantages make organic electroluminescent devices suitable for use in portable electronic devices.
An organic electroluminescent device may include an organic layer such as a hole transport layer, an emission layer, an electron transport layer, and the like. The thickness of an organic layer determines the efficiency, driving voltage, and color coordinate of the organic electroluminescent device.
As the thickness of the emission layer increases, an organic electroluminescent device that includes the emission layer has increased efficiency. At the same time, however, the driving voltage of the organic electroluminescent device also increases.